Optomechanical wavelength and energy conversion in high- double-layer cavities of photonic crystal slabs.

We demonstrate that ultrasmall double-layer photonic-crystal-slab cavities exhibit a very high-Q value for a wide range of the layer spacing, which enables us to realize unique optomechanical coupling. By mechanically varying the separation, we can achieve extraordinarily large wavelength conversion. In addition, the light stored in the cavity can generate a large radiation force. We show that this system exhibits extremely high energy conversion efficiency between optical and mechanical energy, leading to a novel approach for the optomechanical control of light and matter.

All-optical flip-flop circuit composed of coupled two-port resonant tunneling filter in two-dimensional photonic crystal slab.

We propose an optical flip-flop circuit composed of two-port resonant-tunneling filters based on a two-dimensional photonic crystal slab with a triangular air-hole lattice. This circuit can function as an optical digital circuit that synchronizes input data with a clock. In this report, we demonstrate that this circuit can achieve a fast operating speed with a response time of about 10 ps and a low operating power of 60 mW by employing a two-dimensional FDTD calculation.

Ultrasmall multi-port channel drop filter in two-dimensional photonic crystal on silicon-on-insulator substrate.

We demonstrate ultrasmall five-port channel drop filters (CDFs) based on a two-dimensional photonic crystal slab. We combine seven photonic crystals with different lattice constants and use light reflections at the different photonic crystal boundaries to control the interference process and achieve a high dropping efficiency. We operate the CDFs in two modes; one requires careful control of the interference process, whereas the other does not. The former can output a narrower signal spectrum than the latter, and CDF design is easier with the latter. Both CDFs achieve a high dropping efficiency and can function in the CL-band.

Fast bistable all-optical switch and memory on a silicon photonic crystal on-chip.

We demonstrate extremely low-power all-optical bistability by utilizing silicon photonic crystal nanocavities, based on the plasma effect of carriers generated by two-photon absorption. Owing to the high quality factor and the small volume of the nanocavities, the photon density inside the cavity becomes extremely high, which leads to a large reduction in operation power. Optical bistable operation in a single nanocavity permits optical read-write memory operation, which opens the possibility of an integrated optical logic circuit on a single chip, based on photonic crystals. The demonstrated bistable threshold power is 0.4 mW with a set pulse energy of 74 fJ, at a switching speed of <100 ps.

Optical bistable switching action of Si high-Q photonic-crystal nanocavities.

We have demonstrated all-optical bistable switching operation of resonant-tunnelling devices with ultra-small high-Q Si photonic-crystal nanocavities. Due to their high Q/V ratio, the switching energy is extremely small in comparison with that of conventional devices using the same optical nonlinear mechanism. We also show that they exhibit all-opticaltransistor action by using two resonant modes. These ultrasmall unique nonlinear bistable devices have potentials to function as various signal processing functions in photonic-crystal-based optical-circuits.

Ultrasmall multi-channel resonant-tunneling filter using mode gap of width-tuned photonic-crystal waveguide.

We have devised an ultra-small multi-channel drop filter based on a two-port resonant tunneling system in a two-dimensional photonic crystal with a triangular air-hole lattice. This filter does not require careful consideration of the interference process to achieve a high dropping efficiency. First we develop three-port systems based on a two-port resonant tunneling filter. Next we devise a multi-port channel drop filter by cascading these three-port systems. In this paper, we demonstrate a ten-channel drop filter with an 18 mum device size by 2D-FDTD calculation, and a three-port resonant tunneling filter with 65+/- 20 % dropping efficiency by experiment.